Disclosed herein are methods for sequentially analyzing a biological sample to discern inter alia the presence, absence, concentration, and/or spatial distribution of multiple biological targets in a biological sample.
Various methods may be used in biology and in medicine to observe different targets in a biological sample. For example, analysis of proteins in histological sections and other cytological preparations may be performed using the techniques of histochemistry, immunohistochemistry (IHC), or immunofluorescence. Analysis of proteins in biological samples may also be performed using solid-state immunoassays, for example, using the techniques of western blots.
Many of the current techniques may detect only a few targets at one time (such as, IHC or fluorescence-based western blots where number of targets detectable is limited by the fluorescence-based detection system) in a single sample. Further analysis of targets may require use of additional biological samples from the source limiting the ability to determine relative characteristics of the targets such as the presence, absence, concentration, and/or the spatial distribution of multiple biological targets in the biological sample. Moreover, in certain instances, a limited amount of sample may be available for analysis or the individual sample may require further analysis. Thus, methods, agents, and devices capable of iteratively analyzing an individual sample are needed.